Trucking Shipments

This example combines both continuous and discrete dynamics to model the transport of a material by truck to a dock where the material is loaded onto ships.

A stockpile accumulates material continuously at a rate that varies stochastically on a monthly basis. A truck can take material from the stockpile to the dock once per day. Every day, the model checks to see if the dock is currently at capacity (accounting for in-transit trucks). If it is not, a discrete withdrawal of material from the stockpile occurs, and this is transported (over a specified time period) via a truck to the dock. Material accumulates at the dock in discrete amounts and is loaded onto a ship when the dock reaches capacity and a ship is available. Ships arrive at an average rate of once every 5 months. Note that if the dock is full and no ships are available, material accumulates in the stockpile.